Though red squirrels are a solitary and territorial species, a 22-year study of these squirrels in the Yukon suggests that they have a higher chance of survival and a greater number of offspring when living near the same neighbors year after year. Surprisingly, the findings—appearing December 17 in the journal Current Biology—show that it didn't matter whether the squirrels' neighbors were related to them; these fitness benefits instead depended on familiarity, or the length of time the same squirrels lived next to each other. These benefits were even more pronounced in older squirrels, whom the data suggested could sharply offset the effects of aging by maintaining all of their neighbors from one year to the next.